BRINVILLIERS, MARIE MADELEINE MAR GUERITE D'AUBRAY, MARQUISE DE (c. 163o-1676), French poisoner, daughter of Dreux d'Aubray, civil lieutenant of Paris, was born in Paris about 163o. In 1651 she married the marquis de Brinvilliers, then serving in the regiment of Normandy. Contemporary evidence describes her at this time as a pretty and much-courted little woman, with a fascinating air of child like innocence. In 1659 her husband introduced her to his friend Godin de Sainte-Croix, whose mistress she became. Her father then secured the arrest of Sainte-Croix on a lettre de cachet. When Sainte-Croix left the Bastille he plotted with his willing mistress his revenge upon her father. She undertook to experiment with the poisons which Sainte-Croix, possibly with the help of a chemist, Christopher Glaser, prepared, and found subjects ready to hand in the poor who sought her charity and the sick whom she visited in the hospitals. Meanwhile Sainte-Croix determined that not only M. Dreux d'Aubray but also the latter's two sons and other daughter should be poisoned, so that the marquise and himself might come into possession of the family fortune. In Feb. 1666, the marquise poisoned her father, and in 167o, with the connivance of their valet La Chaussee, her two brothers. Before any attempt could be made on the life of Mlle. Therese d'Aubray, Sainte-Croix died suddenly (1672), his glass mask having fallen off while he was preparing his poisons. The police were called in, and discovered among his belongings documents incriminating the marquise and La Chaussee. The latter was arrested, tortured into a complete confession, and broken alive on the wheel (1673), but the marquise took refuge in a convent at Liege, whence she was decoyed by a police emissary disguised as a priest. A full account of her life and crimes was found among her papers. She was taken to Paris, tortured and beheaded, and her body burned on July 16, 1676.